The present invention relates, in general, to electron emission display devices, and more particularly, to a novel electron emission source.
Field Emission Devices (FEDs) are well known in the art and are commonly employed for a broad range of applications including image display devices. Such FEDs typically utilize a matrix of row and column conductors that are used to stimulate electron emission from emitters connected to the column conductors. Also, a ballast resistor typically is used in series between each emitter and the corresponding column conductor. One method of forming such ballast resistors includes applying a resistive layer on a substrate. On top of the resistive layer the column conductor is formed with a grating-like conductor structure. Between cross-members of the conductor's grating-like structure, mesh type openings expose portions of the resistive layer. Emitters are positioned within the meshes on the resistive layer. Such grating-like conductor structures and meshes are described in U.S. Pat. No. 5,194,780 issued to Robert Meyer on Mar. 16, 1993. As described in the above referenced patent, within each mesh a matrix of approximately 36 emitters is formed in order to emit electrons.
One notable disadvantage of such prior art FEDs is the distance of each emitter from the conductor. Within each mesh, current flows from the conductor, through the resistive material to the emitters. Because the distance of each emitter from the conductor varies, the resistance between the conductor and each emitter also varies, thus, the current to each emitter also varies. In some cases, interior emitters may be sufficiently far from a conductor to prevent electron emission. Consequently, it is difficult to accurately control emitters and the corresponding image formed by electrons emitted from the emitters.
Accordingly, it is desirable to have an electron source having emitters that are not at different distances from a column conductor, that do not have different ballast resistor values, and that do not emit different currents.